So I live in an area where I usually have 1 cell bar, and lucky if the call doesn't drop. I usually use free VoIP like Google Hangouts for calls but thinking of upgrading to Yosemite if Phone Calls can be managed through my much more reliable internet connection. My question is, does Yosemite phone calls use VoIP? Or does it simply bluetooth in the phone call and maintain that cell connection? Anyone have experience with this?